Newest servants:
Phoenix Wright: with the a luck stat of EX and Mind of the Eye (true) and Mind of the Eye (false) EX
Godot: with a clairvoyance ability of E, and Noble phantasm of FIRE LAZER and COFFEE

and heres some more i found

(this one isnt really a cross over but it got me thinking) the ultimate servant?

Tsukihime drinking game. 1. Every time a word or a phrase is repeated 3 or more times, take a drink (eg. This chair).
2. Every time Shiki claims not to understand something already explained, take a drink
3. Every time Shiki doesn't realize someone is hitting on him, take a drink.
4. Every time someone who should be dead, isn't, take a drink.
5. Every time Shiki does something ridiculous with points\lines.